• Korean Journal Plant Pathology
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• v.14 no.1
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• pp.99-101
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• 1998

A severe brown rot on peach fruit caused by a Phytophthora sp. has occurred at peach orchards in Taegu of Korea from late June to early August in 1997. Infected fruits showed irregularly round or circular water soaking brown regions. In the severe case, fruits were entirely rotten and surface of the fruits were wrinkled. Occasionally, white mycelia and abundant sporangia were developed on the surface of fruit. Inner tissues of the fruits were also discolored to brown. The causal fungus was identified as Phytophthora cactorum based on following characteristics. Sporangia were ovoid, conspicuously papillate, caducous and measured as 28.4~48.1$\times$21.9~37.2 (av. 39.9$\times$30.4) ${\mu}{\textrm}{m}$. Sexuality of the fungus was homothallic. Oogonia were 25.0~34.0 (av. 29.9) ${\mu}{\textrm}{m}$ in size. Most antheridia were paragynous and measured av. 10.5$\times$13.0 ${\mu}{\textrm}{m}$. Optimum temperature for mycelia growth was around 25~3$0^{\circ}C$. However none of the isolates grew under 7$^{\circ}C$ and over 35$^{\circ}C$. The fungus revealed high pathogenicity to fruits, shoots and leaves of peach, apple and pear with different degrees. Phytophthora fruit rot of peach caused by Phytophthora cactorum has not been reported in Korea previously.

• ALGAE
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• v.26 no.4
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• pp.327-331
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• 2011

An analysis of the vegetative and reproductive anatomy of Sargassum lapazeanum was performed based on extensive sampling in three areas within its geographical range: a) San Juan de la Costa, b) Punta Calera, c) Punta Machos. Material was collected from low intertidal to subtidal populations and evaluated based on variations present within and between populations. Our goal was to comprehensively analyze the features of the vegetative and reproductive anatomy of this species. Our observations showed that this species has cauline, which is anatomically composed of three tissues layers. This species is dioic, with male and female conceptacles in the same receptacle but with different maturation times. The present study confirmed the presence of cauline in this species; this structure was previously described for some species in the Gulf of California, such as Sargassum horridum, and for several species in Japan. This structure could be responsible for the growth of primary branches and may also generate a new plant. This trend might explain the perennial nature of this species at the population level. Field and laboratory experiments could help to delimit the ecophysiological conditions under which this structure starts to develop.

• The Plant Pathology Journal
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• v.19 no.6
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• pp.288-290
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• 2003

Shoot blight of suckers of common lilac plants (Syringa vulgaris) was found in an apartment garden in Daegu, Korea. The causal organism was a species of Phytophthora, which was homothallic with paragynous antheridium. Oogonia were globose and measured 21.5-34.0 $\mu\textrm{m}$ with an average of 29.7$\pm$3.2 $\mu\textrm{m}$ in diameter. Oospores in oogonia were round, light orange brown when mature, mostly plerotic, and measured an average of 25.6$\pm$3 $\mu\textrm{m}$ in diameter. Antheridia were ovoid and around 11.7$\times$7.8 $\mu\textrm{m}$. Sporangia seldom formed on agar media but formed abundantly in water. Sporangia that formed in water were semipapillate, ovoid obpyriform, non-caducous, and 23.4-66.3$\times$17.6-37.1 $\mu\textrm{m}$ in dimension with I/b ratio of 1.46. The causal organism was identified as Phytophthora citricola Sawada on the basis of morphological characteristics. This is the first report of shoot blight caused by P. citricola Sawada in lilac suckers in Korea.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.458-462
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• 1998

Stem rot symptomof lily caused by Phytophthora was observed in Chilkok, Korea in 1997. Oogonia of Phytophthora were abundantly developed on epidermal tissues of stem and leaves of the diseased plants. The casual fungus was identified as Phytophthora cactorum based on their cultural and morphological characteristics. Sporangia were markedly papillate and the shape was broadly spherical to ovoid both on agar and in water. The size was 28~44$\times$20~28 ${\mu}{\textrm}{m}$ (av. 36~24) and a short pedicel was attached to each sporangium. The fungus was homothallic and oogonia were 28~32 ${\mu}{\textrm}{m}$ (av. 30) in size and slightly yellow. Antheridia were paragynous and spherical or irregularly club shaped. Optimal temperature for mycelial growth was 25~27$^{\circ}C$. The fungus did not grow under 6$^{\circ}C$ and over 34$^{\circ}C$. The fungus was highly pathogenic to three cultivars of lily. Symptom was developed at 4-day after artificial inoculation with zoospores (103 cell/ml) on the stem of lily. The symptom was identical to those produced by natural infection in the field and the plant was blighted within 14 days after inoculation.

• The Plant Pathology Journal
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• v.19 no.6
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• pp.291-293
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• 2003

Leaf spot and blight disease of tree peony (Paeonia suffruticosa Andr.) was found in an apartment garden in Daegu in May 2003 for the first time in Korea. The causal organism was identified as Phytophthora cactorum (Leb. And Cohn) Schroeter. The causal fungus was homothallic, and produced distinctively papillate, ovoid to subspherical, and caducous sporangia with pedicel. Sporangia that formed in water measured 23.4-42.9$\times$21.5-35.1 $\mu\textrm{m}$ in range with an average of 35.3$\pm$4.6${\times}$26.9$\pm$36.0 $\mu\textrm{m}$, I/b ratio=1.31, papillae approximately 3.7 $\mu\textrm{m}$ high, and pedicels 2.8 $\mu\textrm{m}$ long. Oogonia were spherical and 21.5-37.1 $\mu\textrm{m}$ in diameter with an average of 29.6$\pm$4.9 $\mu\textrm{m}$. Oospores were spherical, mostly plerotic, and light orange brown when mature, and measured 19.5-31.2 $\mu\textrm{m}$ in diameter with an average of 25.2$\pm$4.4 $\mu\textrm{m}$. Antheridia were almost ovoid or club-shaped and 1l.7-15.6$\times$9.8-11.7 $\mu\textrm{m}$ in size.

• The Plant Pathology Journal
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• v.23 no.1
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• pp.31-33
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• 2007

Phytophthora rot on broad bean(Vicia faba) occurred in the experimental field at Gyeongsangnam-do Agricultural Research and Extension Services from 2004 to 2006. The fungus isolated from the diseased plants grew well on potato dextrose agar and showed an arachnoid or rosaceous colony pattern. Sporangia were conspicuously papillated, noncaducous, ovoid to globose, and $25-64{\times}18-44{\mu}m$ in size. Oogonia and oospores were spherical and measured as 20-32 ${\mu}m$ and 16-28 ${\mu}m$ in size, respectively. Oospores were relatively small and aplerotic. Antheridia were amphigynous, spherical, and unicellula. Chlamydospores were globose and 18-40 ${\mu}m$ in size. Optimum temperature for growth was about $28^{\circ}C$ on potato dextrose agar. The disease occurred in all parts of the plant including roots, stems, leaves and pods in the field. The symptoms similar to those of naturally infected plants were induced by artificial inoculation and the pathogen was re-isolated from the plant. On the basis of mycological and pathological characteristics, the causal pathogen of broad bean rot was identified as Phytophthora nicotianae. This is the first report of Phytophthora rot of broad bean caused by P. nicotianae in Korea.

• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.139-144
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• 1997

A destructive collar rot of apple caused by a species of Phytophthora has widely occurred in Kyungbuk and less extended in Chungbuk, Chungnam and Chunbuk provinces of Korea. Significantly higher incidence of the disease was observed on cv. Fuji when M26 or M9 was used as dwarfing stocks. Incidence of the disease at several orchards in Uisung, Kunwi, Yesan and Muju ranged from 45 to 80%. Twenty-five isolates of the causal fungus were collected and all isolates were identified as P. cactorum on the basis of their cultural and morphological characters. The fungus produced markedly papillate and broadly ovoid deciduous sporangia both on agar and in water, and a short pedicel was attached to each sporangium. Oospores were readily formed on clarified V8 agar by single isolates and all the antheridia were paragynous. The fungus neither grew nor produced oospores under 5 and over 33$^{\circ}C$. The destructive collar rot of apple caused by P. cactorum has not been reported in Korea previously.

• The Korean Journal of Mycology
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• v.25 no.4 s.83
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• pp.276-290
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• 1997

Eleven species of Pythium were identified from 125 isolates collected from leaf blight lesions on creeping bentgrass (Agrostis palustris Huds.), Kentucky bluegrass (Poa pratensis L.), and zoysiagrasses (Zoysia japonica Steud., and Z. matrella (L.) Merr.) at 35 golf courses in Korea in $1990{\sim}1996$. The identified species included P. aphanidermatum, P. arrhenomanes, P. catenulatum, P. graminicola, P. myriotylum, P. oligandrum, P. periplocum, P. rostratum, P. torulosum, P. ultimum var. ultimum, and P. vanterpoolii. Mycological characteristics of sporangia, oogonia, antheridia, and oospores observed on the sucrose-asparagine bentgrass leaf culture medium were described for each species. Of the species, P. arrhenomanes, P. catenulatum, P. gmminicola, P. oligandrum, P. periplocum, P. rostratum, P. torulosum and P. vanterpoolii were reported for the first time in Korea. P. myriotylum, P. rostratum, P. torulosum and P. vanterpoolii showed characteristic colony patterns on the potato-carrot agar medium, which can be used as criteria for species identification of Pythium.

• The Plant Pathology Journal
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• v.21 no.3
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• pp.293-296
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• 2005

A leaf blight caused by a species of Phytophthora was found on fatsia plants (Fatsia japonica Decne et Planch.) growing in an apartment garden in Daegu, Korea in late April to May, 2003. The species of Phytophthora isolated from the diseased plants produced sporangia and sex organs on V8 juice agar medium. Sporangia were papillate, ovoid to subspherical, and caducous with a pedicel. The dimensions of the sporangia were $31.2-46.8\times23.4-33.2{\mu}m$ in range, $39.6\pm4.1\times28.3\pm2.8{\mu}m$ in $average{\pm}standard$ deviation, I/b ratio approximately 1.40, with papillae about $3.6{\mu}m$ high, and pedicels $0.9­5.8{\mu}m$ long. Oogonia were spherical, $25.0-32.5{\mu}m$ in range with an average of $28.2\pm2.3{\mu}m$ in diameter. Antheridia were predominantly paragynous, globose to ovoid, $8.8-13.8\times7.5-10.0{\mu}m$ with an average of $10.9\pm1.2 \times9.2\pm1.1{\mu}m$. Oospores in the oogonia were aplerotic or plerotic, and $20.0-25.0{\mu}m$ in diameter with an average of $23.5\pm1.5{\mu}m$. Pathogenicity of the isolate was confirmed on detached leaves of fatsia. The disease was observed only in April and May of 2003 when the weather was unusually wet. It then diminished with increase of temperature in the year and did not appear again on the same plants in 2004. Thus, the fungus appeared to be a relatively weak pathogen of fatsia.

• Research in Plant Disease
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• v.10 no.1
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• pp.13-16
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• 2004

A basal stem rot disease of potato (Solanum tubersum) grown on hydroponic system in greenhouse was found in Jeju-city, Jeju Province of Korea in January 2001. The symptoms occurred on basel stem and root, and than plants eventually were died. The casual fungus isolate from basal stem rot symptom and identified to be Pythium myriotylum on the basis of mycological characteristics; Main hyphae wide were 8.4 ${\mu}{\textrm}{m}$ in size. Oogonia were spherical, smooth, mostly terminal in shape and 26.4∼31.2 ${\mu}{\textrm}{m}$ in size. Antheridia were 9.6∼14,4${\times}$4.8-9.6 ${\mu}{\textrm}{m}$ in size. Oospores were spherical, smooth, aplerotic in shape and 21.6∼26.4 ${\mu}{\textrm}{m}$ in size. This is the first report on the basal stem rot of potato caused by P. myriotylum in Korea.